1. Field of the Invention
The present invention relates to an ink jet unit and an ink jet recording apparatus mounted with the ink jet unit.
2. Description of Related Art
An ink jet head unit used in a conventional ink jet recording apparatus will be described.
FIG. 41 is a perspective view showing a conventional ink jet head unit, and FIG. 42 is a front view showing a head and a flat cable in the ink jet head unit of FIG. 41.
As shown in FIGS. 41 and 42, the conventional ink jet head unit includes a head 20 from which ink is ejected, a head base 21 on which the head 20 is mounted, and two flat cables 22a, 22b which are attached to the head 20 and pulled out from the head 20 in two different directions. In midway positions of the flat cables 22a, 22b, drivers 23a, 23b that generate ink ejection signals for driving the head 20 are respectively provided. Heat radiating plates 24a, 24b, for efficiently radiating heat generated during operation, are attached to the drivers 23a, 23b. In the head 20, two nozzle arrays 20a, 20b of which each comprises many nozzle holes are formed, and ink is ejected from these nozzle holes.
In such an ink jet head unit, conventionally, mounted parts 25a, 25b are formed between the nozzle arrays 20a, 20b and side portions of the head, and the flat cables 22a, 22b are fixed at the mounted parts 25a, 25b onto the head 20.
Here, the head 20 is composed of a laminate of thin films constituting the nozzle hole, a pressure chamber, an ink flow path, and an actuator. These thin films are weak in close attachment power in the vicinity of the side portions. Therefore, the mounted parts 25a, 25b must be formed not in the vicinity of the side portions of the head but at portions which are distant from the side portions, that is, on the insides of the side portions.
According to the conventional construction, the mounted part must be formed on the inside of the head. Therefore, a dead space is formed between the mounted part and the side portion of the head, so that the size of the head becomes large.
Here, in the case where the flat cable pulled out from the head is bent with a small curvature, since there is a fear of breaking of wire, it must be bent with a curvature of some degree. In this case, in the conventional ink jet head unit in which the mounted part is formed between the nozzle array and the side portion of the head, the flat cable sticks out of a width W of the head orthogonal to a surface of the flat cable.
In the conventional construction, not only the head itself is made large but also the pull-around space of the flat cable connected to the head is required in the width direction. Therefore, the ink jet head unit itself becomes large, which is contrary to a market request of miniaturization.